Field of the Invention
The present invention relates to an illumination apparatus.
Description of the Related Art
In macro photographing for capturing an image of a subject at near distance, an illumination apparatus having a circumferentially ring-shaped or arc-shaped light-emitting section at the end of an imaging lens is often used. Japanese Patent Application Laid-Open No. 2001-215574 discusses an illumination apparatus having a ring-shaped light-emitting unit including a plurality of arc-shaped light sources, such as xenon tubes, arranged along the circumference of an imaging lens.
However, the illumination apparatus discussed in Japanese Patent Application Laid-Open No. 2001-215574 uses, as light sources, glass tubes which are generally manufactured as a straight tube type such as a xenon tube, by processing the glass tubes into an arc shape (bent tube type) through high-accuracy bending processing. As a result, there arises a problem that the cost of light sources increases and accordingly the illumination apparatus becomes expensive. Further, sufficient performance cannot be achieved in terms of the light usage efficiency and light distribution because it is difficult to efficiently and uniformly irradiate a subject (target of macro photographing) with light emitted from such a plurality of bent tube type light sources. Furthermore, this type of illumination apparatus is required to be as small as possible since it is carried and used together with a camera (and exchangeable imaging lenses).